title: Capillary electrophoresis-mass spectrometry reveals the distribution of carbon metabolites during nitrogen starvation in Synechocystis sp. PCC 6803.
abstract: Nitrogen availability is one of the most important factors for the survival of cyanobacteria. Previous studies on Synechocystis revealed a contradictory situation with regard to metabolism during nitrogen starvation; that is, glycogen accumulated even though the expressions of sugar catabolic genes were widely upregulated. Here, we conducted transcript and metabolomic analyses using capillary electrophoresis-mass spectrometry on Synechocystis sp. PCC 6803 under nitrogen starvation. The levels of some tricarboxylic acid cycle intermediates (succinate, malate and fumarate) were greatly increased by nitrogen deprivation. Purine and pyrimidine nucleotides were markedly downregulated under nitrogen depletion. The levels of 19 amino acids changed under nitrogen deprivation, especially those of amino acids synthesized from pyruvate and phosphoenolpyruvate, which showed marked increases. Liquid chromatography-mass spectrometry analysis demonstrated that the amount of NADPH and the NADPH/NADH ratio decreased under nitrogen depletion. These data demonstrate that there are increases in not only glycogen but also in metabolites downstream of sugar catabolism in Synechocystis sp. PCC 6803 under nitrogen starvation, resolving the contradiction between glycogen accumulation and induction of sugar catabolic gene expression in this unicellular cyanobacterium.
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan; PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Osanai
authors.forename: Akira
authors.initials: A
authors.lastname: Oikawa
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Shirai
authors.forename: Ayuko
authors.initials: A
authors.lastname: Kuwahara
authors.forename: Hiroko
authors.initials: H
authors.lastname: Iijima
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
mesh_terms: D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism*; D002952:Citric Acid Cycle; D019075:Electrophoresis, Capillary; D015964:Gene Expression Regulation, Bacterial; D006003:Glycogen / Q000378:metabolism; D013058:Mass Spectrometry; D055442:Metabolome; D009584:Nitrogen / Q000378:metabolism*; D011687:Purines / Q000378:metabolism; D011743:Pyrimidines / Q000378:metabolism; D013217:Starvation / Q000235:genetics; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*
chemical_list: D011687:Purines; D011743:Pyrimidines; D002244:Carbon; D006003:Glycogen; D009584:Nitrogen